It is well-known to treat portions of the human body with a hot or cold compress to aid in healing muscle injury, surgical wounds, etc. One very convenient way of applying such a compress is with a flexible pad with interconnecting passages through which is circulated a hot or cold fluid, usually water, by means of a small pump. Temperature of the fluid is controlled by a heater in the pump, or with refrigeration or an ice bath external of the patient contact pad.
Because of the wide variation of curves, angles, etc. of the human anatomy, it is common practice to fold the fluid circulating pad to provide a more precise contour and size of the pad against a particular portion of the patient's body. For instance, applying a flat pad to an elbow or ankle area usually requires some bending or folding of the pad. In hospitals, it is also common practice to fold the pad as one might fold a blanket simply to reduce its size to 1/4 or so of its normal unfolded size.
Such folding has created problems in flexible fluid circulating pads because often the fold causes a crimp in the fluid circulating passages, which stops or slows down the circulation through the pad. This can seriously affect the maintenance of a constant temperature to the patient, i.e. hot or cold. Liquid circulates better through a folded patient treatment pad when the liquid can flow randomly in several different directions. Thus, if one small area of the pad has a particularly tight crimp, the liquid seeks the passage of least resistance and can detour around the particular flow restricting crimp. Random interconnecting flow patterns are shown in FIG. 2 of the Herndon U.S. Pat. No. 396,208 and Holland U.S. Pat. No. 735,876.
A patient treatment pad has been proposed, the Gaymar T-pad, which includes a series of round "button" seals that provide a random passage between the buttons over generally the entire patient contact area of the pad. A narrow inlet channel along one edge of the pad and a narrow outlet channel along another edge of the pad is provided by a row of buttons more closely spaced together than the remaining buttons of the pad. Except for the narrow inlet and outlet channels, the entire pad has a random circulation pattern around the round buttons.
The above types of random fluid flow pads would help reduce the flow restriction caused by folding the pad. However, this same round button pattern over substantially the entire patient treatment area of the pad causes liquid to take the path of least resistance in a folded pad, and certain areas of the pad would have little or no circulation. For instance, if an inlet were at one corner of a rectangular pad and an outlet at a diagonally opposite corner, most flow would occur between the diagonally opposite inlet and outlet and the other two corner areas would have much slower circulation, if any. This uneven circulation would cause temperature variations throughout the pad.